I don't know if this is cool or quite sad, but i was quite impressed when i found this.

Try putting this in a php file and see what you get

<?php

echo '<img src="' . $_SERVER['PHP_SELF'] . '?=' . php_logo_guid() . '" />';

?>

http://www.php.net/manual/en/function.php-logo-guid.php

Spoiler:

There's one for zend, too

Would have been less sad if the logo had some anti-aliasing